Merchants do not have access to the CC numbers, the payment processor does. And even if they did, what you're proposing would be far more work than it's worth. If you wanted to, you could get a list of email addresses from accounts that have submitted excessive chargebacks, and put in some form validation logic that prevents them from making further transactions.

Merchants probably don't have enough information to do that themselves, but it does seem like a service a provider like Stripe would be happy to provide.

I have a feeling the ML fraud models such as Stripe radar encodes some of that, even if unintentionally.

i run a startup. I would be extremely willing to join a shared blacklist API. If this comment gets votes, I will make a service and populate it with data from our end.

Ethoca basically facilitates this.